const path = require('path');
const baseWebpackConfig = require('./webpack.config');
const config = require('./config');
const utils = require('./utils');
const webpack = require('webpack');
const merge = require('webpack-merge');
const CopyWebpackPlugin = require('copy-webpack-plugin');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const OptimizeCSSPlugin = require('optimize-css-assets-webpack-plugin');
const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
const ExtractTextPlugin = require('extract-text-webpack-plugin');

const env = require('./prod.env');

const webpackConfig = merge(baseWebpackConfig, {
    devtool: config.build.productionSourceMap ? config.build.devtool : false,
    output: {
        path: config.build.assetsRoot,
        filename: utils.assetsPath('js/[name].[chunkhash].js'),
        chunkFilename: utils.assetsPath('js/[id].[chunkhash].js')
    },
    plugins: [
        // http://vuejs.github.io/vue-loader/en/workflow/production.html
        new webpack.DefinePlugin({
            'process.env': env
        }),
        new UglifyJsPlugin({
            uglifyOptions: {
                compress: {
                    warnings: false
                }
            },
            sourceMap: config.build.productionSourceMap,
            parallel: true
        }),
        // extract css into its own file
        new ExtractTextPlugin({
            filename: utils.assetsPath('css/[name].[contenthash].css'),
            // Setting the following option to `false` will not extract CSS from codesplit chunks.
            // Their CSS will instead be inserted dynamically with style-loader when the codesplit chunk has been loaded by webpack.
            // It's currently set to `true` because we are seeing that sourcemaps are included in the codesplit bundle as well when it's `false`,
            // increasing file size: https://github.com/vuejs-templates/webpack/issues/1110
            allChunks: true,
        }),
        // Compress extracted CSS. We are using this plugin so that possible
        // duplicated CSS from different components can be deduped.
        new OptimizeCSSPlugin({
            cssProcessorOptions: config.build.productionSourceMap
                ? { safe: true, map: { inline: false } }
                : { safe: true }
        }),
        // generate dist index.html with correct asset hash for caching.
        // you can customize output by editing /index.html
        // see https://github.com/ampedandwired/html-webpack-plugin
        new HtmlWebpackPlugin({
            filename: config.build.index,
            template: 'index.html',
            inject: true,
            minify: {
                removeComments: true,
                collapseWhitespace: true,
                removeAttributeQuotes: true
                // more options:
                // https://github.com/kangax/html-minifier#options-quick-reference
            },
            // necessary to consistently work with multiple chunks via CommonsChunkPlugin
            chunksSortMode: 'dependency'
        }),
        // keep module.id stable when vendor modules does not change
        new webpack.HashedModuleIdsPlugin(),
        // enable scope hoisting
        new webpack.optimize.ModuleConcatenationPlugin(),
        // split vendor js into its own file
        new webpack.optimize.CommonsChunkPlugin({
            name: 'vendor',
            minChunks (module) {
                // any required modules inside node_modules are extracted to vendor
                return (
                    module.resource &&
                    /\.js$/.test(module.resource) &&
                    module.resource.indexOf(
                        path.join(__dirname, '../node_modules')
                    ) === 0
                )
            }
        }),
        // extract webpack runtime and module manifest to its own file in order to
        // prevent vendor hash from being updated whenever app bundle is updated
        new webpack.optimize.CommonsChunkPlugin({
            name: 'manifest',
            minChunks: Infinity
        }),
        // This instance extracts shared chunks from code splitted chunks and bundles them
        // in a separate chunk, similar to the vendor chunk
        // see: https://webpack.js.org/plugins/commons-chunk-plugin/#extra-async-commons-chunk
        new webpack.optimize.CommonsChunkPlugin({
            name: 'app',
            async: 'vendor-async',
            children: true,
            minChunks: 2  //抽取复用组件的使用次数下限
        }),

        // copy custom static assets
        new CopyWebpackPlugin([
            {
                from: path.resolve(__dirname, '../static'),
                to: config.build.assetsSubDirectory,
                ignore: ['.*']
            }
        ])
    ]
});

module.exports = webpackConfig;